Having developed a procedure for purifying cow nose desmosomes in large quantities and having characterized their macromolecular constituents, we are in the process of localizing these constituents in the ultrastructure of the desmosome. To accomplish this, we are perfecting technique for affinity labelling structures within plastic-embedded thin sections for electron microscopy. We couple this technique with the use of affinity probes such as lectins and monoclonal antibodies directed against identified desmosomal constituents. In this manner, we have already made progress in revealing the molecular anatomy of the desmosome.